1. Ye Li Graduate Student UW – Madison
An Investigation on Part of the Work Done by the B Physics Group at CDF
Ye Li
Graduate Student
UW – Madison

2. 1. New Heavy Baryons Σb and Σb*
Only Λb0 Directly Observed Before
Heavy Quark Effective Theory (HQET)
Heavy Quark: mQ→Infinity
Good Quantum Numbers: Angular Momentum & Flavors ( of light quarks )
Two Light Quarks: Diquark ( 3×3 = )
Antisymmetric Λ- type (Isospin I=0)
Symmetric Σ- type (Isospin I=1)

3. Theoretical Prediction:
Spins
Spin - 3/2: Σ* ( complete flavor symmetry of three quarks )
Spin - 1/2: Σ & Λ ( partially antisymmetric configuration )
Theoretical Prediction:

4. The Fully Reconstructed Decay Mode
Σb*±→Λb0π±; Σb±→Λb0π±;
Λb0→Λc+π¯, Λc+→p K¯ π+
Measurement Result (Unit: Mev/c2)
m(Σb+)  = (stat.) ± 1.7(syst.)
m(Σb¯) = (stat.) ± 1.7(syst.)  
m(Σb*+) = (stat.) ± 1.7(syst.)
m(Σb*¯) = (stat.) ± 1.7(syst.)

6. 2. Measurement of B Lifetime and Extraction of ΔΓCP/ΓCP
Two-body Charmless Decays of Bs and Bd
Bs → K+ K-
Bs → K+ π-
Bd → K+ π-
Bd → π+ π-
First measurement of Their Lifetimes
Measurement (Unit: ps)
τ(Bd) = 1.51 ± 0.08(stat) ± 0.02(syst)
τ(Bs→K+K-) = 1.53 ± 0.18(stat) ± 0.02(syst)

7. Combine the Latest HFAG Average of the Bs Lifetime in Flavor Specific Decays: τ(Bs FS)= ± ps
Result
ΔΓCP/ΓCP (Bs→ K+K-) = ± 0.23 ± 0.03

8. My Question:
Does flavor specific decay here refer to the decays of pure Bs or Bs-bar?
Is ΔΓCP the decay width with CP breaking, and ΓCP the decay width with CP conserved?
What is q1 in the expression of α parameter? (see the diagram on the next slide)
How to read the Likelihood scans on the next slide?

10. Likelihood Scan

11. 3. The Rare Decays Bs(d)→ μ+ μ-
Powerful Tool to Probe for Physics beyond the SM
SM prediction: BR( Bs → μμ ) ≈ 3.8x10-9
Branching Ratio Enhanced in Various Extensions to the SM

12. Result: World's best limits
BR( Bs → μμ ) < 1.0 x 95% CL BR( Bd → μμ ) < 3.0 x 95% CL
BR( Bs → μμ ) < 8.0 x 90% CL BR( Bd → μμ ) < 2.3 x 90% CL

14. ?

15. 4. Measurement of the relative cross sections of χc1 & χc2
Based on 1.1 fb-1
χc → J/ψ γ
Measurement (B.F.= Branching Fraction)
 σ(χc2)/σ(χc1) = 0.70 ± 0.04 (stat.)± 0.04 (sys.)± 0.06 (B.F.),  for prompt production
 σ(χc2)/σ(χc1) = 0.25 ± 0.07 (stat.)± 0.01 (sys.)± 0.02 (B.F.),  for B decay production

17. My Questions:
Can we measure the cross section directly, not just the ratio between two cross sections?
Why PT is so important? Why we never consider the momentum in the longitudinal direction, just because it’s hard to measure?
What is the prompt production?

18. Thank You
All data and plots acquired from CDF B physics group internal webpage